1// -*- C++ -*-
 2#include "Rivet/Analysis.hh"
 3#include "Rivet/Projections/Beam.hh"
 4#include "Rivet/Projections/UnstableParticles.hh"
 5
 6namespace Rivet {
 7
 8
 9  /// @brief BABAR Lambda_c from fragmentation
10  ///
11  /// @author Peter Richardson
12  class BABAR_2007_I725377 : public Analysis {
13  public:
14
15    RIVET_DEFAULT_ANALYSIS_CTOR(BABAR_2007_I725377);
16
17
18    void init() {
19      declare(Beam(), "Beams");
20      declare(UnstableParticles(), "UFS");
21
22      book(_histOff  ,1,1,1);
23      book(_sigmaOff ,2,1,1);
24      book(_histOn   ,3,1,1);
25      book(_sigmaOn  ,4,1,1);
26    }
27
28
29    void analyze(const Event& e) {
30      // Loop through unstable FS particles and look for charmed mesons/baryons
31      const UnstableParticles& ufs = apply<UnstableParticles>(e, "UFS");
32
33      const Beam beamproj = apply<Beam>(e, "Beams");
34      const ParticlePair& beams = beamproj.beams();
35      const FourMomentum mom_tot = beams.first.momentum() + beams.second.momentum();
36      const LorentzTransform cms_boost = LorentzTransform::mkFrameTransformFromBeta(mom_tot.betaVec());
37      const double s = sqr(beamproj.sqrtS());
38      const bool onresonance = fuzzyEquals(beamproj.sqrtS(), 10.58*GeV, 2E-3);
39
40      // Particle masses from PDGlive (accessed online 16. Nov. 2009).
41      for (const Particle& p : ufs.particles()) {
42        // Only looking at Lambda_c
43        if (p.abspid() != 4122) continue;
44        MSG_DEBUG("Lambda_c found");
45        const double mH2 = 5.22780; // 2.28646^2
46        const double mom = FourMomentum(cms_boost.transform(p.momentum())).p();
47        const double xp = mom/sqrt(s/4.0 - mH2);
48
49        if (onresonance) {
50          _histOn  ->fill(xp);
51          _sigmaOn ->fill(Ecm);
52        } else {
53          _histOff ->fill(xp);
54          _sigmaOff->fill(0.5);
55        }
56      }
57    }
58
59
60    void finalize() {
61      scale(_sigmaOn , 1./sumOfWeights());
62      scale(_sigmaOff, 1./sumOfWeights());
63      scale(_histOn  , 1./sumOfWeights());
64      scale(_histOff , 1./sumOfWeights());
65    }
66
67
68  private:
69
70    // Histograms for the continuum cross sections
71    BinnedHistoPtr<string> _sigmaOn;
72    Histo1DPtr _sigmaOff;
73    Histo1DPtr _histOn  ;
74    Histo1DPtr _histOff ;
75    const string Ecm = "10.58";
76
77  };
78
79
80
81  RIVET_DECLARE_ALIASED_PLUGIN(BABAR_2007_I725377, BABAR_2007_S6895344);
82
83}